Carbon black reactor having a reactor throat

ABSTRACT

A new reactor for the production of carbon black, a method for the production of carbon black, and a carbon black are disclosed. The carbon blacks are characterized by a surface area preferably in the range of 70 to 150 m 2  /g and &#34;G&#34; values of either less than 1.20 or greater than 1.85, corresponding to very narrow or very broad aggregate size distributions, respectively. The reactor is preferably for axial flow of combustion gases and is characterized by serial arrangement of a cylindrical combustion zone, a frustoconical converging zone, a throat, an abrupt diverging zone and a cylindrical pyrolysis zone. In certain aspects of the invention, the combustion gases are formed by combusting low BTU fuel and forcing these gases through the throat at a velocity approaching Mach 1. In one method of carbon black production, the feedstock is introduced into the converging zone. In another method, it is introduced as a spray. In other methods, the feedstock is introduced with upstream or downstream velocity components.

This is a division of copending application Ser. No. 534,217, filedSept. 20, 1983, now abandoned which is a continuation-in-part ofcopending application Ser. No. 413,202, filed Aug. 30, 1982, nowabandoned.

In one aspect, the invention relates to new carbon black reactors. Inanother aspect, the invention relates to new methods for producingcarbon black. In yet another aspect, the invention relates to novelfurnace-type carbon black products.

Although commercial vortex flow reactors are adequate for today's needs,changes to provide greater economy and flexibility of operation and evenhigher quality product could be desirable.

For example, improvements in the efficiency at which carbon black isproduced from the feedstock would be very desirable. Also, theproduction of a carbon black product which contains exceptionally lowlevels of "grit" would be very desirable. The capability of producingcarbon blacks having extremely positive or extremely negative tintresiduals would also be desirable.

In accordance with the invention, the above objectives are satisfied.

In one aspect, the present invention provides a composition of mattercomprising a carbon black characterized by a CTAB surface area ofbetween about 50 and 500 m² /g and an aggregate size distributionbreadth index G of 1.85 or greater. This type of carbon black impartslow hysteresis properties to rubber into which it has been compoundedand can therefore be very desirable for the production of belts andtires, for example.

In another aspect, the present invention provides a compositioncomprising a carbon black characterized by a CTAB surface area ofbetween about 50 and 500 m² /g and an aggregate size distributionbreadth index G of 1.20 or less. This type of carbon black has a highpositive tint residual value which imparts high abrasion resistance intires.

In a further aspect of the invention, there is provided a compositioncomprising a carbon black characterized by a CTAB surface area in therange of 60-140 m² /g and a numerical value for the DBP structure whichis at least 1.4 times the numerical value of the CTAB surface area.

In a still further aspect of the invention, there is provided acomposition comprising a carbon black characterized by a CTAB surfacearea in the range of 60-140 m² /g and numerical values for DBP and24M4-DBP structures such that the numerical value for the differencebetween the DBP and 24M4-DBP is less than about 0.2 times the DBP value.

In still another aspect of the present invention there is provided acarbon black reactor formed by refractory which defines a reaction flowpath comprising in series from an upstream end and in generally axialalignment (a) a generally cylindrical combustion zone characterized by agenerally annular upstream end wall defining a passage generally axiallydirected into the generally cylindrical combustion zone; (b) a generallyfrustoconical mixing zone characterized by a sidewall converging fromthe sidewall of the generally cylindrical combustion zone, said sidewallhaving ports therethrough for the receipt of feedstock injectors; and(c) a generally cylindrical pyrolysis zone defined by a generallycylindrical sidewall connected to the downstream end of the mixing zoneby a generally annular end wall. This reactor is well-adapted forproducing carbon black at high yields and low grit levels.

In yet another aspect of the present invention, there is provided for aprocess of producing carbon black comprising flowing a stream of hotcombustion gases having a temperature sufficiently high to decompose acarbonaceous feedstock and form carbon black sequentially through aconverging zone, a throat and an abruptly diverging zone and introducingthe carbonaceous feedstock transversely into the stream of hotcombustion gases from the periphery of the stream for decomposition toform the carbon black, the improvement comprising introducing thecarbonaceous feedstock as a coherent stream into the converging zone.The improvement step results in greater yields of product which has ahigher tint residual.

In another aspect of the present invention there is provided for aprocess of producing carbon black comprising flowing a stream of hotcombustion gases having a temperature sufficiently high to decompose acarbonaceous feedstock and form carbon black sequentially through aconverging zone, a throat and an abruptly diverging zone and introducingthe carbonaceous feedstock transversely into the stream of hotcombustion gases from the periphery of the stream for decomposition toform the carbon black, the improvement comprising introducing thecarbonaceous feedstock into the throat within a distance of about 4inches from the abruptly diverging zone. The improvement step results inthe production of low or negative tint residual black which imparts lowhysteresis to rubber into which it has been compounded.

In another aspect of the present invention there is provided for aprocess of producing carbon black comprising flowing a stream of hotcombustion gases having a temperature sufficiently high to decompose acarbonaceous feedstock and form carbon black sequentially through aconverging zone, a throat and an abruptly diverging zone and introducingthe carbonaceous feedstock transversely into the stream of hotcombustion gases from the periphery of the stream for decomposition toform the carbon black, the improvement comprising introducing thecarbonaceous feedstock into the stream of hot combustion gases as acoherent stream having a velocity component counter to the flow of thestream of hot combustion gases.

In still another aspect of the present invention there is provided for aprocess of producing carbon black comprising flowing a stream of hotcombustion gases having a temperature sufficiently high to decompose acarbonaceous feedstock and form carbon black sequentially through aconverging zone, a throat and an abruptly diverging zone and introducingthe carbonaceous feedstock transversely into the stream of hotcombustion gases from the periphery of the stream for decomposition toform the carbon black, the improvement comprising introducing thecarbonaceous feedstock as a spray into at least one of the convergingzone and the throat. The improvement step results in the production ofcarbon black at higher efficiency than where coherent streams offeedstock are utilized.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE illustrates certain features of one embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

According to the invention, an apparatus 2 comprises, serially arranged,a combustion zone 4, a mixing zone 6, and a pyrolysis zone 8.

Preferably, the combustion zone 4 comprises a combustion chamber 10defined by a preferably generally cylindrical sidewall 12 and agenerally annular upstream end wall 14 having a passage 16 therethroughgenerally axially directed into the generally cylindrical combustionchamber 10. The sidewall 12 and endwall 14 are generally formed from arefractory material to resist high temperatures.

Oxidant fluid and combustible fluid are introduced into the chamber 10via the passage 16. Preferably, the passage 16 leads from chamber 18which is defined by a housing 20. The housing 20 can be formed frommetal, such as steel, and preferably comprises a generally tubularsidewall 21 so that the chamber 18 is generally cylindrical as itextends from the passage 16, preferably in axial alignment therewith. Atubular member 23 extends through the chamber 18 axially and emptiesinto the passage 16. In the preferred embodiment, the tubular member 23carries the combustible fluid which is mixed with oxidant fluid from thechamber 18 in the passage 16. The housing 20 is closed at its upstreamend by a plate 24 affixed to a flange 26 which circumscribes theupstream end of the housing 20. The tubular member 23 enters the chamber18 in an axial direction through the plate 24. An annulus 19 definedbetween the plate 24 and the tubular member 23 provides a passage forthe introduction of coolant, such as a cool gas, into the chamber 18 toprotect the metal components in the neighborhood of flange 24 from hightemperatures. A duct 27 opens into the chamber 18 through the sidewall21. The duct 27 can open into the chamber 18 tangentially if desired,although a duct opening into the chamber 18 generally normally withrespect to the longitudinal axis of the chamber 18 has been used withgood results.

Preferably, the generally annular surface 14 is a part of a ring orchoke 28 positioned between the chambers 18 and 10 and defining thepassage 16, because the ring helps to distribute oxidant fluid from thechamber 18 into the chamber 10. The ring 28 can be formed from a sectionof tubular refractory. The tubular member 23 preferably empties into thepassage 16 through a plurality of radially outwardly directed ports ororifices 30 passing through the sidewall of the tubular member 23 wherea gaseous combustible fluid is utilized, for ease of fabrication andreliability of operation. A bluff body, preferably a generally annularflange 29 is attached to the tubular member 23 slightly downstream ofthe ports 30 to aid in maintaining stable combustion. Preferably, theflange 29 is positioned upsteam of the surface 14, most preferably about2 inches into the zone 16, as measured from zone 18.

Generally, the reaction flow passage expands between the passage 16 andthe zone 10 from a first diameter to a second diameter such that theratio between the first diameter and the second diameter is betweenabout 0.3 and about 0.8. Usually, the ratio of the diameters of theflange 29 and the passage 16 is within the range of from about 0.5 toabout 0.75.

The mixing zone 6 comprises a sidewall 31 formed from refractorydefining a chamber 32 in axial alignment with and converging from thecombustion chamber 10 to a throat 34 and a means 36 for introducing acarbonaceous feedstock through the sidewall 31 and into at least one ofthe converging chamber 32 and the throat 34. Preferably, the convergingchamber 32 converges from an inlet havin a diameter about the same asthat of the combustion chamber 10 to an outlet having a diameter aboutthe same as that of the throat 34. A converging chamber which convergesat a half-angle of about 18°30' has been used with good results. Themeans 36 comprises one or more sets of ports 38, which open into thechamber 32, more preferably, 2 or more sets of ports 38 with at leastone set opening into the converging chamber 32 and at least one setopening into the throat 34 for the positioning of carbonaceous feedstockinjectors 40. Usually, the ports of a set will be circumferentiallyspaced about the reaction flow passage at a selected position withrespect to the longitudinal axis of the reaction flow passage, with theports being preferably equiangularly spaced from each other for uniformdistribution of feedstock from the injectors 40 and into the reactionflow passage. Generally, each set of ports 38 will be arranged inequiangular spacing, for example, 180°, 120°, 90°, or 60°, and beradially inwardly directed, although they can be canted upstream ordownstream as desired. Ports not in use can be sealed with plugs 41.Usually, the injectors 40 will be positioned through only one set of theports 38 so that they empty into the flow passage of the reactor at thesame longitudinal position. As injectors are moved upstream, thestructure of the black increases. Preferably, the tip of each injectoris positioned about flush with the reactor wall, to lessen heat exposureand cut down on coking and plugging.

Alternatively, the injectors 40 can be provided with nozzles 43 whichcan be canted to introduce carbonaceous feedstock into the reaction flowpassage with an upstream or downstream velocity component as desired.The nozzles 43 can be selected to introduce the feedstock as a coherentstream or a spray or any other pattern as desired. When the feedstock isintroduced into the reactor in a partially upstream or downstreamdirection, preferably upstream with a component counter current to theflow of combustion gases to improve mixing it is preferred that thenozzles be selected to emit a coherent stream of feedstock, so that thedissociation of the feedstock will take place away from the reactor walland the penetration of the feedstock will be sufficient to cause gooddistribution of dissociated carbonaceous material across the reactionflow path. Where the feedstock is to be introduced generally normallyinto the reactor with respect to its axis, it is currently preferred toutilize nozzles which are designed to emit a spray, although spraynozzles are also advantageous where the nozzles are canted, especiallywhen the nozzles are canted to emit feedstock in a downstream direction.It appears that when spray-stream nozzles are used, product yield fromthe reactor is enhanced over when solid-stream nozzles are used.Solid-cone type spray nozzles, which emit atomized feedstock at an angleof divergence of about 15° have been used with good results. Oil nozzleswhich emit the feedstock in a cone-shaped spray which diverges at anangle in the range of 15° to about 140° are thus generally suitable. Oilnozzles which emit a cone-shaped spray which diverges at an angle in therange of 30° to about 120° are preferred, since it appears that furtherincreases in yield are obtained at angles of above 30° and about 120° isnear the angle at which feedstock deposition on the reactor wall maycause operating problems. Most preferably, the nozzle should be onewhich emits a spray in a cone which diverges at an angle in the range of45° to 90°, since runs with 60° nozzles show an unexpectedly high yieldwhen compared to 15° or 30° nozzles. Jacket cooling air, not shown, cansurround the oil injectors 40, flowing through the annulus between theoil tube and the wall of the port.

When the apparatus is operated with carbonaceous feedstock injectioninto the throat 34, carbon black having a wide aggregate sizedistribution can be produced. Generally, for this type of operation, thefeedstock injectors will be positioned about 0;14 4 inches, for examplebetween 1 and 3 inches, upstream of the pyrolysis zone. Such a carbonblack is frequently characterized by a negative tint residual and willimpart low hysteresis to rubber into which it has been compounded. Whenthe apparatus is operated with feedstock injection into the convergingchamber 32, carbon black having a very narrow aggregate sizedistribution can be produced. Such a carbon black is frequentlycharacterized by a high or positive tint residual. Generally, for thistype of operation, the feedstock or oil injectors 40 will be positionedbetween about 4 inches and about 36 inches upstream of the pyrolysiszone, usually between about 6 and about 24 inches upstream.

If desired, carbonaceous feedstock can also be injected into theconverging chamber 32 and/or throat 34 via optional axial feedstockinjector assembly 42, which can be fitted with an appropriate nozzle todispense liquid or vaporous, preferably liquid, carbonaceous feedstock.In some operations, tube 42 is not installed, however, in the preferredembodiment of this aspect of the invention, the assembly 42, whichpreferably comprises a feedstock tube 47 coaxially disposed within awaterjacket tube 45, enters the reactor 2 coaxially within the gas tube23 and extends adjustably from the end of the tube 23 at least into theconverging chamber 32. The feedstock tube 47 can be fitted with any oneof a variety of feedstock nozzles, for example, single or multiple solidjet nozzles with the jets directed axially, radially outwardly, or at anangle, or a solid or a hollow cone nozzle, etc., as desired.

The pyrolysis zone 8 preferably is comprised of one or more generallycylindrical sections of refractory material 44. The mixing zone 6 ispreferably a separate section of refractory, so that it can be easilyreplaced if desired.

Because of very high temperatures in zone 8, heavy-duty refractory, suchas chrome-alumina refractory (minimum 9 wt. % Cr₂ O₃) manufactured byDidier-Taylor, Cincinnati, Ohio, is preferably employed for at least theconstruction of the zone 8.

It is desired to generate high turbulance in the reaction mixture whenit passes from the mixing zone 6 to the pyrolysis zone 8, todisintegrate the carbonaceous feedstock to form high quality carbonblack. It is therefore very important that the reaction flow passageundergo an abrupt expansion as it enters the pyrolysis zone from themixing zone. Preferably, the half-angle of expansion is near 90°,because this configuration has been used with good results.

Preferably, the upstream end of the pyrolysis zone is defined by agenerally annularly shaped end wall 46 which extends from the downstreamend of the throat 34 to the upstream end of pyrolysis zone sidewall 48.The pyrolysis zone preferably has a generally circular cross-section ina plane normal to the axis of the reaction flow passage. The desiredamount of expansion between the zones will depend on reactor flowconditions and the desired properties of the carbon black to beproduced. Generally, the cross sectional area of the reaction flowpassage defined by sidewall 48 in a plane normal to the reactor axiswill be in the range of from about 2 to about 20, preferably about 2.8to about 13 times larger than the cross sectional area of the reactionpassage at the throat 34. An expansion ratio toward the lower end ofthis range tends to provide a carbon black product characterized byhigher surface area and lower structure, while an expansion ratio towardthe upper end of the range provides a carbon black product characterizedby lower surface area and higher structure.

Where the production of a carbon black product characterized by higherstructure is desired, the pyrolysis zone is provided with a plurality ofabrupt expansions in the reaction flow passage. In the FIGURE, theupstream end off the pyrolysis zone 8 comprises serially arranged fromthe upstream end wall 46 a first generally cylindrical zone 50 having afirst diameter and a second generally cylindrical zone 52 having asecond diameter which is larger than the first diameter. Preferably, thefirst generally cylindrical zone 50 has a diameter sufficient so thatthe area ratio between the first generally cylindrical zone 50 and thethroat 34 is in the range of from about 2:1 to about 20:1, morepreferably about 2.8:1 to about 13:1. The flow area ratio between thesecond generally cylindrical zone 52 and the first generally cylindricalzone 50 is preferably from about 1:1 to about 4:1. The first generallycylindrical zone 50 preferably has a length in the range of from about0.1 to about 15 times the diameter of the throat 34, usually from about0.5 to about 10 diameters. Preferably, an annular shoulder 54 separatesthe zones 50 and 52, because this design provides a good flow pattern.

The pyrolysis zone 8 is further provided with a means 56 for supplyingcooling fluid to the reaction flow passage. Generally, the means 56comprises ports 58 opening into the pyrolysis zone 8. Preferably, atleast one of the ports 58 carries a tube and spray nozzle assembly 60for introducing a quench fluid into the zone 8 to stop the pyrolysisreaction. Generally, the means 56 will be positioned downstream of theoutlet of the throat at a distance of from about 5 to about 45 throatdiameters, usually at a distance of between about 8 and about 20 throatdiameters. In other terms, the means 56 will be positioned between about1.5 feet and about 20 feet downstream of the throat. Positioning themeans 56 close to the throat produces low photolometer product. Usually,the means 56 is positioned downstream from the throat at a distance toproduce a photolometer value of at least about 70 and is preferablydesigned to spray water. Further downstream of the quench means 56, thereaction mixture is further cooled to facilitate handling, and can beprocessed in conventional equipment.

Certain aspects of the invention are carried out according to a processcomprising flowing a stream of hot combustion gases having a temperaturesufficiently high to decompose a carbonaceous feedstock and form carbonblack sequentially through a converging zone, a throat and an abruptlydiverging zone; and introducing the carbonaceous feedstock transverselyinto the stream of hot combustion gases from the periphery of the streamfor decomposition to form the carbon black.

Generally, the oxidant fluid comprises air, since it is inexpensive andplentiful, preferably preheated air at a temperature of from about 700°to about 1250° F., since employing preheated air is an inexpensivemethod of supplying heat to the reactor to drive the pyrolysis reactionand aids in forming a high-structure product. Of course, pure oxygen oroxygen-enriched air is also suitable, and besides having the advantageof producing a higher structure product, is the preferred oxidant wherea low BTU fuel is burned.

Generally, the combustible fluid will comprise mostly methane, becausemethane is the major component of natural gas and synthetic natural gasand these materials are suitable combustible fluids and are inexpensive.Other combustible fluids, containing one or more components, for exampleselected from hydrogen, carbon monoxide, acetylene and propane are alsosuitable. An inexpensive fuel commonly found in a carbon black plantcomprises off-gases from the filter bags, especially from soft blackmanufacture. This fuel is a low-BTU fuel, containing about 100 BTU/SCF,and generally 25-30 vol% or so of H₂ and CO.

Liquid fuels such as are used in some conventional carbon black plantscan also be used in the present invention. In some plants part of thefeedstock is used as fuel.

Generally, stoichiometric or excess air is mixed with the combustiblefluid and ignited as the mixture is introduced into the combustion zone.By stoichiometric is meant an amount which results in the essentialabsence of both molecular oxygen and combustible materials in thecombustion gases. A greater than stoichiometric amount of air, commonlycalled "excess" air, will result in the presence of reactive oxygen inthe combustion gases. Fifty percent excess air is frequently used incarbon black manufacturing processes, and this means that 150% of thestiochiometric amount of air has been mixed with the combustible fluid.

Of course, the "excess" air partly consumes the carbonaceous feedstockand therefore results in lost yield. There are at least two reasons,however, why its presence can be desirable. First, as the excess airreacts with the feedstock, it generates both turbulence and heat, andtherefore a finer and more uniform carbon black product. Secondly, theexcess air dilutes the combustion gases and reduces their temperature,protecting equipment. However, where the reactor is capable ofwithstanding the temperatures of near stoichiometric combustion of theair and fuel and concommitantly generates sufficient turbulencedownstream of the feedstock injection to form the desired particle sizeof carbon black, and the combustion gas stream contains sufficient heatto pyrolyze the feedstock particles, excess air can be avoided, since itresults in reduced yields due to combustion of a portion of thefeedstock.

Where natural gas is used as the combustible fluid, it is preferablymixed with air at a volume ratio of from about 10:1, which is nearstoichiometric, to about 20:1, which would be about 100% excess air. Atreactor conditions, the combustion gases pass through the throat at atemperature in the range of 2400°-3000° F., and at a velocity generallyin the range of Mach 0.2-1.0, usually between about 0.3 to about 0.7.Mach 1 in feet per second is roughly equal to 49.01√T, where T is thetemperature in °R (Rankine) at reactor conditions, (T°R=T°F+460). Highertemperatures and velocities yield desirable products, but cause undulyexpensive operation.

The carbonaceous feedstock which is injected into the combustion gasstream from its periphery is generally any of the hydrocarbon feedssuitable for forming carbon black. Generally, the carbonaceous feedstockwill be a liquid, contain about 90 weight percent carbon and have adensity greater than that of water. Preferably, the feedstock will becharacterized by a Bureau of Mines Correlation Index, BMCI of betweenabout 90 and about 150. The carbonaceous feedstock is preferablypreheated to a temperature in the range of 250° to about 500° F. or evenup to 750° F., if plant equipment will so provide, prior to injectioninto the combustion gases although 700° F. may be a safer upper limit toavoid thermal cracking. Preheating the oil feed to at least 350° F. willassist in dispersal. It is important that the streams of feedstock donot penetrate sufficiently far to impinge on the wall of the reactor.However, to insure adequate dispersal, it is preferred that thefeedstock be injected at a pressure of at least 50 psig. Where the oilspray diverges at an angle of above 15°, pressures above 100 psig suchas in the range of 150 to 600 psig are even more preferable, as theywill provide better dispersal of the feedstock. Pressures in the rangeof 200-400 psig, for example, are rather easily achievable and areexpected to provide high yields of product. If desired, the samecarbonaceous feedstock can also be introduced into the reactor from aposition along the reactor axis. It will be appreciated that injectingthe feedstock through a smaller orifice requires a higher pressure toachieve the same penetration.

According to certain aspects of the present invention, the carbonaceousfeedstock is introduced into the converging zone from the peripherythereof.

By injecting the carbonaceous feedstock transversely into the convergingcombustion gases, there can be provided a novel carbon black producthaving a CTAB surface area in the range of between about 50 and about500 m² /g, usually between about 50 and about 200 m² /g, most preferablybetween about 70 and 150 m² /g, which is characterized by a "G index"value of less than about 1.2, between about 1.0 and 1.2, such as between1.1 and 1.2 preferably between 1.15 and 1.20. This type of carbon blackcan be characterized by a tint residual of about plus 12 or greater andoccasionally plus 16 or greater (See tabulated runs in subsequenttables.). Such a carbon black can be usefully compounded into rubber toimpart certain desirable properties thereto. The CTAB surface area of acarbon black sample is measured in accordance with ASTM and is generallyconsidered to have a correlation with the surface area of the carbonblack sample available for reinforcing rubber. The "G index" value iscalculated in accordance with Applied Optics 19, 2977 (1980) and asherein described in Example III and correlates with the breadth ofdistribution of the aggregate particle sizes in the sample. A "G index"value of less than 1.25 indicates an extremely homogeneous product, withthe sizes of the aggregates being extremely uniform, relativelyspeaking. "Conventional" furnace blacks have a "G index" value in therange of about 1.4-1.6.

The carbonaceous feedstock can be introduced into the converging zoneeither as a coherent stream or as a spray, as desired. Preferably, thefeedstock is introduced as a spray, because testing shows that sprayingthe feedstock into the reactor results in the higher yield of product.The feedstock can be introduced into the converging zone in a directionnormal to the axis of the reactor flow path, which is preferred, sinceit has been tested with good results, or it can be introduced into thecombustion gases with a flow component cocurrent or countercurrent tothe combustion gas flow. Where the feedstock is to be introduced intothe reactor with a flow component countercurrent to the flow of thecombustion gas stream, it may be desirable to utilize a coherent streamof feedstock, to mitigate impingement of feedstock on the reactor wall.

According to another aspect of the invention the carbonaceous feedstockis sprayed inwardly into the combustion gas stream flowing through thereactor throat, preferably radially inwardly, or, if desired, canted inthe upstream or preferably, the downstream direction. Spraying thefeedstock into the throat as a mist produces a higher surface areaproduct than injecting coherent streams of feedstock into the throatunder reactor conditions which are otherwise the same. Because theinvention in this embodiment provides a method raising the surface areaof the carbon black product at no increase in operating costs, it is asignificant advance in the art.

In another aspect of the present invention, by introducing thecarbonaceous feedstock radially inwardly transversely into thecombustion gas stream downstream of the inlet to the converging sectionat a distance upstream of the pyrolysis section in the range of fromabout 0.05 to 0.9 throat diameters, preferably in the range of 0-4inches upstream of the pyrolysis zone, more preferably in the range of1-3 inches upstream of the pyrolysis zone, such as about 1.5 inchesupstream of the pyrolysis zone, there can be provided a novel carbonblack product having a CTAB surface area in the range of between about50 and about 500 m² /g, usually between about 50 and about 200 m² /g,preferably between about 70 and about 150 m² /g, which is characterizedby a "G index" value of greater than about 1.85, preferably greater thanabout 2, such as in the range of 2 to 3, preferably between about 2.25and about 2.75. This type of carbon black can be characterized by a tintresidual value of minus 12 or lower and occasionally minus 16 or lower(See tabulated runs in subsequent tables.). A carbon black characterizedby high "G index" value has a broad aggregate size distribution andimparts low hystersis properties to rubber into which it has beencompounded. This carbon black will impart low rolling resistance tovehicular tires when it has been compounded into the rubber which formsthem.

In yet another aspect of the invention, by introducing the carbonaceousfeedstock radially inwardly as a spray transversely into the combustiongas stream at a distance upstream of the beginning of the reactor throatof at least 1 reactor throat diameter, such as in the range of 1-3throat diameters upstream of the reactor throat novel carbon blackshaving an abnormal relationship between surface area and structure canbe produced. These carbon blacks can be usefully compounded intovehicular tire treads, usually with from about 1 to about 5 parts byweight of rubbery polymer for each part by weight of carbon black. TheCTAB surface area of these blacks will generally fall in the range of60-140 m² /g, usually in the range of 75-130 m² /g, and preferably inthe range of about 80 to about 125 m² /g, as much of the carbon blackused in tire treads has a CTAB surface area in the range of 95-115 m²/g. The structure of the blacks can be reduced by introducing structuremodifying agents such as materials containing potassium into the carbonforming zone. Without potassium injection, the novel blacks exhibit aDBP value of at least about 1.4 times the numerical value of their CTABsurface area, preferably at least about 1.5 times the CTAB surface area,such as in the range of about 1.5 to about 1.8 times the CTAB surfacearea. Potassium injection can be used to reduce structure, but therelationship between surface area and structure remains abnormal. Thereduction in structure caused by potassium usage is abnormally small.The structure difference as measured by the DBP and 24M4-DBP proceduresbecomes less striking. Generally speaking, the novel carbon blacksexhibit a difference in their DBP and 24M4-DBP values of less than about0.2 times the DBP value, usually less than about 0.15 times the DBPvalue, such as in the range of about 0.05 to about 0.15 times the DBPvalue. Phrased another way, the value obtained for structure by the24M4-DBP test is between 80 and 100%, usually between 83 and 97 percent,of the value obtained by the DBP test. For inventive carbon blackshaving a CTAB surface area in the range of 80 to about 125 m² /g, theDBP structure will usually be in the range of about 85 to about 130cc/100 g.

The invention is illustrated by the following Examples.

EXAMPLE I

The runs were made in a pilot plant reactor. A is the diameter of zone10. B is the diameter of throat 34. C is the diameter of zone 52. D isthe length of zone 10. E is the length of zone 32. α is the angle atwhich the sidewall of zone 32 converges toward the longitudinal axis ofthe reactor. F is the length of throat 34. G is the length of zone 52from wall 46 to quench 60. H is the distance of oil injectors 40upstream from wall 46, and J is the diameter of zone 16. The gas burnerupstream of zone 10 was modified from that shown by the FIGURE asfollows:

Premixed air and fuel were supplied axially into the passage 16 throughthe end of a tube having a 4 inch inside diameter and terminating 2"upstream of wall 14. The end of the tube was partially closed by aradially inwardly extending annular flange having an inside diameter of2.5 inches. Results are shown in Table I.

    TABLE I      RUN NUMBER 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18       Reactor                   Dimensions, Ins. A 6 6 6 6 6 6 6 6 6 6 6 6 6     6 6 6 6 6 B 1.67 1.67 1.67 1.67 1.67 1.67 1.67 1.67 1.67 1.67 1.67 1.67     1.67 1.67 1.67 1.67 1.67 1.67 C 6 4 3 3 3 × 6.sup.(a) 6 6 6 4 4 4     4 4 4 4 6 × 8.sup.(b) 6 × 8.sup.(b) 6 D 6 6 6 6 6 6 6 6 6 6     6 6 6 6 6 6 6 6 E 8.5 8.5 8.5 8.5 8.5 8.5 8.5 8.5 8.5 8.5 8.5 8.5 8.5     8.5 8.5 8.5 8.5 8.5 F 1.5 3.5 3.5 3.5 3.5 1.5 1.5 1.5 1.5 3.5 1.5 1.5     1.5 1.5 3.5 1.5 1.5 1.5 G 36 23 64 72 39 35 33 23 20 25 50 35 25 19 27     72 72 50 (Inlet C to Quench) H 1.5 1.5 6.5 6.5 6.5 1.5 1.5 1.5 1.5 3.5     4.5 4.5 4.5 4.5 6.5 1.5 1.5 1.5 J 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4     α Degrees, 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15 15     Approx. Ratio 3.6 2.4 1.8 1.8 1.8 × 3.6.sup.(a) 3.6 3.6 3.6 2.4     2.4 2.4 2.4 2.4 2.4 2.4 3.6 × 4.8.sup.(c) 3.6 × 4.8.sup.(c)     3.6 C/B Diameters, Nozzle: Orifice Diam. ins. 0.032 0.039 0.039 0.039     0.039 0.032 0.032 0.028 0.039 0.039 0.039 0.039 0.039 0.039 0.039 0.032     0.032 0.032 No. of Nozzles 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 3 3 Spacing,     degrees 180 180 180 180 180 180 180 180 180 180 180 180 180 180 180     .sup.(c) .sup.(c) .sup.(c) PROCESS FLOW Total Air, 14036 14065 14024     13832 14002 13863 13948 14392 13982 14063 14113 14120 14109 14134 14112     14281 14281 10331 SCF/hr. Temperature, °C. 410 414 413 563 562     413 412 410 561 560 563 564 562 561 559 562 562 558 Fuel, SCF/hr. 875     886 884 885 886 879 883 1107 738 733 778 778 778 778 880 730 731 523     BTU/SCF 976 947 948 948 956 964 964 964 964 977 947 947 947 947 977 974     974 974 Air/Fuel Gas. 16 15.9 15.9 15.6 15.8 15.8 15.8 13.0 18.9 19.2     18.1 18.1 18.1 18.2 16.0 19.6 19.5 19.8 Vol. Ratio Oil, GPH 18.7 20.5     22.2 24.5 24.6 22.61 22.6 18.7 22.3 22.0 27.5 24.6 22.3 20.6 20.3 27.3     30.03 18.05 API, 60° F./60° F. -3.2 -3.2 -2 -2 -2 -3.2     -3.2 -3.2 -3.2 -3.2 -2.0 -2.0 -2 -2 -2 -3.2 -3.2 -3.2 Lbs/Gallon 9.19     9.19 9.1 9.1 9.1 9.19 9.19 9.19 9.19 9.19 9.1 9.1 9.1 9.1 9.1 9.19 9.19     9.19 BMCI 140 140 138 138 138 140 140 140 140 140 138 138 138 138 138     140 140 140 Carbon, wt. % 91.5 91.3 91.3 91.3 91.3 91.5 91.5 91.5 91.5     91.5 91.3 91.3 91.3 91.3 91.3 91.5 91.5 91.5 Temperature, °C. 131     157 154 154 153 158 154 152 157 148 155 153 152 150 149 162 162 152     Pressure, psig 150 110 110 125 140 80 50 100 110 105 145 125 110 95 100     120 170 110 Air to Oil, 751 686 632 565 569 613 617 770 627 639 513 574     632 686 695 530 475 572 SCF/gal. PRODUCT CARBON BLACK Lbs/Gal. Feed 4.68     4.7 4.8 5.2 5.3 5.33 5.2 5.6 4.7 4.4 5.0 4.8 4.4 4.1 4.4 5.15 5.44 4.9     CTAB, m.sup.2 /g 108 115 108 105 107 77.5 85 110 122 117 101 113 135 149     137 85 67 91.1 N.sub.2 SA, m.sup.2 /g 117 124 110 105 112 79.7 85 119     131 128 103 120 143 176 155 87 68 95.0 24M4-DBP, 111 96 94 94 106 93.5     101 113 97 97 98 103 105 107 108 98 92 103 cc/100 g Tint 102.3 105.3     123.6 119.8 115.4 81.4 83.3 99.8 105.7 109.1 115.9 122.5 130.7 134.2 128     89.1 75.6 95.1 Tint Residual -5.5 -9.4 +8.9 +7.2 +4.9 -15.3 -16.1 -8.4     -11.6 -5.6 +6.9 +9.9 +10.9 +14.6 +10.5 -10.9 -14.8 -6.8 Photelometer 79     74 77 78 82 75 79 80 84 80 80 73 83 82 82 95 71 85 Lbs Black/Gal ×     505 541 518 546 567 413 442 616 573 515 505 542 594 611 603 438 365 446     CTAB m.sup.2 /g Lbs Black/ 0.5566 0.5602 0.5777 0.6259 0.6379 0.5800     0.5658 0.6094 0.5114 0.4788 0.5495 0.5276 0.4835 0.4505 0.4835 0.6125     0.6469 0.5826 Lb C in Feed Lbs Black/Lb C 60.1 64.4 62.4 65.7 68.3 44.9     48.1 67.0 62.4 56.0 55.5 59.6 65.3 67.1 66.2 52.1 43.3 53.1 in Feed     × CTAB m.sup.2 /g Oil-Lbs Carbon/ 8.41 8.39 8.31 8.31 8.31 8.41     8.41 8.41 8.41 8.41 8.31 8.31 8.31 8.31 8.31 8.41 8.41 8.41 Gallon Lbs     Carbon/Hr-Fuel 27.7 28.1 28.1 28.1 28.1 28.1 28.0 35.1 23.4 23.4 24.6     24.6 24.6 24.6 27.9 25.5 25.8 16.6 Lbs Carbon/Hr-Oil 157.3 172 184.5     203.6 204.4 190.2 190.1 157.3 187.5 185 228.5 204.4 185.3 171.2 168.7     230.1 252.5 151.8 Total Lbs 185 200.1 212.6 231.7 232.5 218.3 218.1     192.4 210.9 208.4 253.1 229 209.9 195.8 196.6 255.6 278.3 168.4 Carbon/Ho     ur Lbs CB/Hour 87.5 96.4 106.6 127.4 130.4 120.5 117.5 104.7 104.8 96.8     137.5 118.1 98.1 84.5 89.3 141.1 164.3 88.4 Lbs CB/Lb-Total C 0.4730     0.4814 0.5014 0.5498 0.5609 0.5520 0.5387 0.5442 0.4969 0.4645 0.5433     0.5157 0.4674 0.4316 0.4542 0.551 0.59 0.5249 Lbs CB/Lb Total C ×     51.1 55.4 54.2 57.7 60.0 42.7 45.8 59.9 60.6 54.3 54.9 58.3 63.1 64.3     62.2 46.8 39.5 47.8 CTAB     .sup.(a) This is a two stage or stepped zone. The 3 inch diameter zone wa     9 inches in length for run 5, and the 6 inch diameter zone was 30 inches     in length to quench injection.     .sup.(b) This is a two stage or stepped zone. The 6 inch diameter zone wa     38 inches long in both runs 16 and 17, and the 8 inch diameter zone was 3     inches in length for both runs;     .sup.(c) 3 nozzles spaced at 90°. Two nozzles are 180°     apart, with the third nozzle in between at 90° from the two nozzle     which are 180°  apart.

Runs 1, 2 and 3 show decreases in air-to-oil ratio, SCF/gallon, of about750, 685, and 630, respectively; decreases in diameter of zone C, ininches, of 6, 4, and 3, respectively; increases in H, in inches, of 1.5,1.5, and 6.5, respectively; and increases in F, in inches, of 1.5, 3.5,and 3.5, respectively, cause increased carbon black production, inpounds per hour, of from 87.5 to 96.4, to 106.6, respectively, withincreases in pounds of carbon black per gallon of feed oil from 4.68, to4.7, to 4.8, respectively. The CTAB values, in m² /g, would be expectedto decrease from run 1 through run 3 because of the decreases inair-to-oil ratio from run 1 through run 3. However, run 1 and run 3 hadthe same 108 CTAB values, and, unexpectedly, run 2 had a very high CTABvalue of 115. The 24 M4 values, in cc/100 g, decreased from 111 to 96 to94, respectively from run 1 through run 3, due to these changes.

When the air preheat was increased from 413° C. for run 3 to 563° C. forrun 4, the production of carbon black increased from 4.8 to 5.2 poundsof carbon black per gallon of feedstock. The CTAB values remained aboutthe same, and the tint residuals were about the same at +8.9 and +7.2,respectively.

Runs 4 and 5 shows that changing the dimensions of C, using a 3 inchdiameter throughout for 72 inches in run 4, but using C of 3 inchesdiameter for 9 inches and then 6 inches in diameter for 30 inches toquench for run 5, there resulted in an extremely large gain in 24M4value for run 5 from 94 for run 4 to 106 for run 5, at about the sameCTAB values and at about the same tint residuals. In addition, thechange in C in run 5 increased the yield of carbon black in pounds pergallon of oil, this quantity being 5.2 for run 4 and 5.3 for run 5.Runs, 1, 2 and 3 had values of 4.68, 4.7, and 4.8, respectively, forcarbon black yields in pounds per gallon.

Runs 6 through 15 show the effects of the position of the oil injectionH on tint residuals. Runs 6 and 7 had H values of 1.5 inches, the oilbeing added 1.5 inches upstream from the throat outlet, and the tintresiduals were -15.3 and -16.1, respectively, for runs 6 and 7. The Hvalues for runs 14 and 15 were 4.5 and 6.5 inches upstream from thethroat outlet, respectively, and the tint residuals were +14.6 and+10.5, respectively, for runs 14 and 15. This change in H shows theflexibility of the operation for producing carbon blacks of broadaggregate distribution (runs 6 and 7) and of narrow aggregate sizedistribution (runs 14 and 15).

Runs 16 and 17 used the two-step reaction zone, as disclosed, and with Hvalues of 1.5 inches, produced tint residuals of -10.9 and -14.8,respectively, using the different nozzle arrangement as compared withruns 1 through 15, as defined herein. The CTAB values were 85 and 67,respectively, using air-to-oil ratios of 530 and 475, respectively, forruns 16 and 17, and tint residuals of -10.9 and -14.8, respectively.

Run 18 used a one-step or 6 inch diameter zone C for the reactor andused the same nozzle arrangement as in runs 16 and 17, with H of 1.5inches, and produced a tint residual of -6.8.

EXAMPLE II

The runs were made in a commercial size plant reactor. A-J were measuredin the same manner as in Example I. A is 28 inches. B is 12 inches. C is20.5 inches. D is 3 feet 9 inches. E is 2 feet. F is 4 inches. G and Hare shown in Table II. J is 18 inches. K is the diameter of flange 29,which seals the end of gas tube 23, and is 10 inches. L is the length ofring 28, and is 14 inches. α is 18°26'. Results are shown in Table II.

    TABLE II      RUN NUMBER 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36       Black Type N299 N299 N299 N299 N299 N299 N299 N299 N299 N299 N299 N299     N299 N299 N351 N351 N299 N299 Reactor Dimensions, Ins. A to F, J & K -     See Above G 9'11" 9'11" 9'11" 9'11" 9'11" 9'11" 9'11" 9'11" 9'11" 9'11"     9'11" 9'11" 9 40 11" 9'11" 14'5" 14'5" 9'11" 9'11" H inches 16 16 16 16     16 16 16 16 16 16 16 16 16 16 16 16 16 16 Oil Nozzle: Number at 60.degree     . spacing 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 Diameter (orifice) 21/8"     21/8" 21/8" 21/8"  21/8" 21/8" 21/8" 21/8" 21/8" 21/8" 21/8" 21/8" 21/8"     21/8" 21/8" 21/8" .sup.(a) .sup.(a)  4 7/64" 4 7/64" 4 7/64" 4 7/64" 4     7/64" 4 7/64" 4 7/64" 4 7/64" 4 7/64" 4 7/64" 4 7/64" 4 7/64" 4 7/64" 4     7/64" 4 7/64"  4 7/64" Type JETS JETS JETS JETS JETS JETS JETS JETS JETS     JETS JETS JETS JETS JETS JETS Jets .sup.(b) .sup.(b) Rates & Conditions     Process Air, MSCFH 657.6 668.8 657.3 653.0 661.8 655.3 656.2 643.4 654.0     649.5 647.3 639.8 639.8 638.0 586.4 586.4 669.8 660 Jacket Air, MSCFH     8.1 8.1 8.1 8.1 8.1 8.1 8.1 8.1 8.1 8.1 8.0 8.1 8.1 7.8 8.3 8.3 8.2 8.1     Total Air, MSCFH 665.7 676.9 665.4 661.1 669.9 663.4 664.3 651.5 662.1     657.6 655.3 647.9 647.9 645.8 594.7 594.7 678.0 668.1 Air Temp, °F     . 1183 1184 1180 1192 1190 1190 1195 1205 1208 1205 1207 1246 1246 1196     1204 1204 1216 1208 Fuel Gas, MSCFH 39.4 39.5 39.5 39.2 40.0 40.0 39.7     38.7 39.6 39.4 39.5 39.3 39.3 38.6 38.8 38.8 40.9 40.6 Fuel Gas, Btu/SCF     869 871 868 875 872 872 867 874 870 868 872 870 870 882 875 875 867 871     Air/Gas Ratio 16.9 17.1 16.8 16.9 16.7 16.6 16.7 16.8 16.7 16.7 16.6     16.5 16.5 16.7 15.3 15.3 16.6 16.5 Oil Rate, gph 1212 1227 1232 1219     1202 1202 1192 1174 1190 1159 1142 1178 1178 1162 1337 1337 1195 1 253     °API 7.1 7.1 7.0 7.0 6.8 6.8 6.8 6.0 6.0 5.6 5.6 5.5 5.5 5.5 6.0     6.0 6.3 6.4 Lb/gal 8.51 8.51 8.51 8.51 8.53 8.53 8.53 8.53 8.58 8.60     8.60 8.60 8.61 8.61 8.58 8.58 8.56 8.55 BMCI 100 100 100 100 101 101 101     103 103 104 104 104 104 104 103 103 102 102 C, wt % 88.4 88.4 88.4 88.4     88.4 88.4 88.4 88.4 88.4 88.4 88.4 88.4 88.4 88.4 88.4 88.4 88.4 88.4     Temp. °F. 450 450 450 450 450 450 450 450 450 450 450 450 450 450     450 450 450 450 Pressure, psig 150 160 155 155 152 150 150 150 150 180     140 145 145 140 180 180 210 220 Air/Oil Ratio, SCF/gal 549 552 540 542     551 552 557 555 556 567 574 550 550 556 445 445 567 57 533 Product * * *     * * * * * * * * ** * * * ** * * Yield, lbs/gal 4.17 4.14 4.18 4.29 4.14     4.21 4.16 4.21 4.28 4.22 4.29 4.38 4.38 -- 4.93 4.93 4.13 4.36 CTAB,     m.sup.2 /g 99 99 97 96 97 96 98 98 99 98 100 101 97 101 72 79 106 94     N.sub.2 SA, m.sup.2 /g 114 113 105 106 107 107 109 111 114 109 118 106     110 114 73 75 129 100 24M4-DBP, cc/100 g 101 102 102 103 101 102 105 101     99 98 101 105 102 101 98 103 102 102 Tint 112 110 110 109 114 112 111     110 112 109 119 118 118 118 102 98 116 111 Tint Residual +8.2 +5.9 +5.4     +5.2 +9.6 +8.0 +7.6 +5.3 +6.7 +3.5 +14.7 +11.2 +13.9 +12.6 +10.0 +2.4     +9.9 +7.7 (Lbs CB/gal) × 413 410 405 412 402 404 409 413 424 414     429 442 425 -- 355 389 438 410 (CTAB) Lbs CB/Lb C in oil 0.554 0.551     0.556 0.570 0.549 0.559 0.553 0.555 0.565 0.555 0.563 0.576 0.576 --     0.650 0.650 0.546 0.577 Lbs CB/Lb C in oil × 54.8 54.5 53.9 54.7     53.3 53.6 54.2 54.4 55.9 54.4 56.3 58.1 55.8 -- 46.8 51.4 57.9 54.2 CTAB     325 mesh grit, wt % -- -- -- -- -- -- -- -- -- -- -- 0.0090 -- -- --     0.0055.sup.(c) --  --                 0.0101.sup.(d)       RUN NUMBER 37 38 39 40 41 42 43 44 45 46       Black Type N299 N299 N299 N234 N234 N234 N299 N299 N234 N299 Reactor     Dimensions, Ins. A to F, J & K - See Above G 9'11" 9' 11" 9'11" 8'2"     8'2" 8'2" 9'11" 9'11" 9'11" 9'11" H inches 16 16 16 16 16 16 6 6 6 6 Oil     Nozzle: Number at 60° spacing 6 6 6 6 6 6 6 6 6 6 Diameter     (orifice) .sup.(a) .sup.(a) Type .sup.(b) .sup.(b) .sup.(e) .sup.(e)     .sup.(e) .sup.(e) .sup.(e) .sup.(e) .sup.(e) JETS Rates & Conditions     Process Air, MSCFH 660 659.9 657.1 666.7 666.7 666.7 659.2 651.2 647.9     659.1 Jacket Air, MSCFH 8.1 8.2 8.3 8.1 8.1 8.1 8.1 8.1 8.1 8.1 Total     Air, MSCFH 668.1 668.1 665.4 674.8 674.8 674.8 667.3 659.3 656.0 667.2     Air Temp, °F. 1208 1204 1211 1201 1201 1201 1201 1194 1200 1213     Fuel Gas, MSCFH 40.6 41.9 41.5 42.1 42.1 42.1 42.0 42.4 42.1 42.1 Fuel     Gas, Btu/SCF 871 867 867 863 863 863 866 865 868 870 Air/Gas Ratio 16.5     15.9 16.0 16.0 16.0 16.0 15.9 15.5 15.6 15.8 Oil Rate, gph 1253 1235     1260 1120 1120 1120 1278 1263 1135 1243 °API 6.4 6.4 6.6 6.9 6.9     6.9 6.9 7.5 7.5 6.9 Lb/gal 8.55 8.55 8.54 8.52 8.52 8.52 8.52 8.48 8.48     8.52 BMCI 102 102 101 100 100 100 100 98 98 100 C, wt % 88.4 88.4 88.4     88.4 88.4 88.4 88.4 88.4 88.4 88.4 Temp. °F. 450 450 450 450 450     450 450 450 450 450 Pressure, psig 220 210 240 190 190 190 240 310 280     210 Air/Oil Ratio, SCF/gal 533 541 528 602 602 602 522 522 578 537     Product ** * * * * ** * * * * Yield, lbs/gal 4.36 4.30 4.46 4.08 4.08     4.08 4.08 4.36 4.15 4.39 CTAB, m.sup.2 /g 96 100 104 119 120 115 100 103     114 100 N.sub.2 SA, m.sup.2 /g 102 112 115 143 141 124 109 109 130 106     24M4-DBP, cc/100 g 103 101 101 102 103 106 104 100 99 97 Tint 109 112     115 120 120 117 114 118 121 112 Tint Residual +4.6 +6.4 +7.4 +9.0 +7.8     +5.5 +8.1 +9.5 +9.0 +3.8 (Lbs CB/gal) × 419 430 464 486 490 469     446 449 473 439 (CTAB) Lbs CB/Lb C in oil 0.577 0.570 0.590 0.542 0.542     0.542 0.593 0.582 0.554 0.583 Lbs CB/Lb C in oil × 55.3 57.0 61.4     64.5 65.0 62.3 59.3 59.9 63.2 58.3 CTAB 325 mesh grit, wt % 0.0022.sup.(c     ) -- -- -- -- 0.0051.sup.(c) -- -- -- --     *Unpelleted     **Pelleted     .sup.(a) 2 tubes, orifice nozzles, 7/64" diameter orifices; and 4 sprays,     1/8 G1514, as shown on page 19 of The Spraying Systems Catalog Number 27.     .sup.(b) 2 orifices or jets, 4 sprays     .sup.(c) Invention run     .sup.(d) Conventional carbon blacks     .sup.(e) 6 sprays, 1/8 G1514, as shown on page 19 of The Spraying Systems     Catalog Number 27.

The photolometer values of blacks of Example II ranged from about 75 toabout 90 (ASTM D 1618-80).

Plant runs 19 through 46 show that different tread blacks are made(N299, N351 and N234) in the operations. Runs 19 through 34 used onlyjets. Runs 35 through 38 used jets and sprays. Runs 39 through 45 usedall sprays. Run 46, again, used all jets.

Comparing runs 37, 38, and 39, producing N299 type carbon black, andusing substantially the same operating conditions, runs 37 and 38 (alljets) produced 4.36 and 4.30 pounds of carbon black per gallon of oil,respectively, while run 39 (all sprays) produced 4.46 pounds of carbonblack per gallon of oil. All had about the same tint residual of +4.6,+6.4 and +7.4, respectively. With the sprays of run 39, higher CTABblack was made (smaller nodules) and unexpectedly at higher yield, thanin runs 37 and 38.

EXAMPLE III

Samples of the blacks obtained from runs 6, 7, 8, 11, 12, 13 and 14above were analyzed according to the following procedure.

Determination of G (Aggregate Size Distribution Breadth Index)

Carbon blacks were dispersed in a 10-mM (10 millimolar) aqueous solutionof sodium dioctylsulfosuccinate, an anionic surfactant trade namedAerosol OT (CAS Registry 577-11-7). The solution was cleaned by passingit through a 0.45-μm Millipore filter before use. Complete dispersion ofthe carbon blacks was accomplished with a magnetically stirredultrasonic cleaning bath (U.S. Pat. No. 3,807,704, issued 1974, licensedto Lako Manufacturing Company). This bath combines mechanical stirringwith ultrasonic agitation to obtain synergistic enhancement of rates ofdispersion. Masterbatch slurries at concentrations of about 2 mg permilliliter (50 mg of black plus 25 milliliters of liquid) were initiallytreated 30 minutes in the bath. These were then diluted 100-fold (250μliter of slurry plus 25 milliliters of liquid) and further sonified for150 minutes. All masses and volumes were determined by weighing on afive-place analytical balance; precise concentrations c (μg/milliliter)were calculated from these weights.

Measurements were made of "dimensionless optical density spectra"defined as

    DODS.sub.obs. ≡ρλc.sup.-1 b.sup.-1 log (Io/I) (I)

wherein ρ is the density of carbon black, taken as 1.85 g/cc. Theremaining symbols have their usual photometric significance and are setout below.

Optical absorbance readings, log (I_(o) /I), were I_(o) is incidentintensity and I is transmitted intensity, were obtained at 50-nmintervals in incident wavelength λ_(o) from 350 to 1000 nm, using aBeckman Model B spectrophotometer and cuvettes having optical pathlength b=10.0 mm. The raw absorbance readings were converted toDODS_(obs) values according to equation I. λ is the wavelength in thesuspension medium of refractive index m₂, and λ=λo/m₂, where λ_(o) isthe vacuum wavelength. For the aqueous medium used, m₂ =1.324+3046/λ_(o)².

To determine G, the theoretical quantity DODS_(calc) is matched with theobserved quantity DODS_(obs) using an iterative least-squares technique.The problem is to find the minimum of ##EQU1## with respect toparameters of the carbon black aggregate size distribution f(X), andwith respect to the complex refractive index, n-k-1, of carbon black.Under the constraint

    [(1-n).sup.2 +k.sup.2 ]/[(1+n).sup.2 +k.sup.2 ]=0.195,     (III)

this can be accomplished by means of a conventionally organizedgeneral-purpose nonlinear least-squares (Gauss-Newton iterative varianceminimization) computer program in which is embedded a fully rigorousMie-theory subroutine for furnishing DODS_(calc) function values and thenecessary partial derivatives, the latter being obtained numerically. Inequation (II), f(X) is a normalized particle diameter distributionfunction and N* denotes statistical degrees of freedom. The expressionfor DODS_(calc) is ##EQU2## where <C_(ext) > is number-averageextinction cross section of the carbon black aggregates, and <πX³ /6> istheir number average volume. C_(ext) is calculated for each aggregatesize X by Mie theory for a sphere of diameter X. The statisticaldistribution of X by frequency was assumed to be of log-normal form:##EQU3## where G is the breadth index for the distribution and X_(g) isthe geometric mean of sphere diameters.

The carbon black samples analyzed exhibited the following "G" values.

    ______________________________________                                               Run 6         G = 2.35                                                        Run 7         G = 2.51                                                        Run 8         G = 2.37                                                        Run 11        G = 1.55                                                        Run 12        G = 1.43                                                        Run 13        G = 1.17                                                        Run 14        G = 1.22                                                 ______________________________________                                        ASTM TESTS USED                                                               ______________________________________                                        CTAB, m.sup.2 /gm      D 3765-80                                              N.sub.2 SA, m.sup.2 /gm                                                                              D 3037-80                                              24M4-DBP, cc/100 gm    D 3493-80                                              Tint                   D-3265-80                                              Photelometer           D 1618-80                                              TR (Tint Residual) (U.S. 4,267,160 - 1981)                                    ______________________________________                                         TR = Tint  [56.0 + 1.057 (CTAB)0.002745 (CTAB).sup.2  0.2596                  (24M4DBP)-0.201 (N.sub.2 SACTAB)                                         

EXAMPLE IV

The runs were made in a commercial size plant reactor. A is 21 inches. Bis 8 inches. C is 15 inches. D is 27 inches. E is 18.5 inches. F is 4inches. G is 7.8 inches. H is 16 inches. J is 12 inches. α is 18°27'.Results are shown in Table III.

                                      TABLE III                                   __________________________________________________________________________    RUN NUMBER   47   48   49   50   51                                           __________________________________________________________________________    Black Type   N299 N299 N299 N299 N299                                         Oil Nozzle:                                                                   No. at 90° spacing                                                                  4    4    4    4    4                                            Diameter (orifice)                                                                         2-.0890"                                                                           3-.0890"                                                                           2-.0890"                                                                           2-.0890"                                                                           .082"                                                     2-.0625"                                                                           1-.0625"                                                                           2-.0625"                                                                           3-.0625"                                          Full Cone Spray Angle                                                                      15°                                                                         15°                                                                         15°                                                                         15°                                                                         60°                                   .sup.(a) Type                                                                              Spray                                                                              Spray                                                                              Spray                                                                              Spray                                                                              Spray                                        Rates & Conditions                                                            Total Air, MSCFH                                                                           199.5                                                                              249.1                                                                              249.3                                                                              198.9                                                                              199.2                                        Air Temp, °F.                                                                       1129 1189 1194 1180 1169                                         Fuel Gas, MSCFH                                                                            13.0 16.4 16.5 12.8 12.8                                         BTU/SCF      957  951  945  949  950                                          Air/Gas Ratio                                                                              15.3 15.2 15.1 15.5 15.6                                         Oil Rate, gph                                                                              345  426  428  343  344                                          °API  -2.3 -2.3 -2.3 -2.3 -2.3                                         Lb/gal       9.127                                                                              9.127                                                                              9.127                                                                              9.127                                                                              9.127                                        BMCI         127  127  127  127  127                                          C, wt %      91.4 91.4 91.4 91.4 91.4                                         Temp. °F.                                                                           331  336  327  328  336                                          Pressure, psig                                                                             104  112  151  140  128                                          Air/Oil Ratio, SCF/gal                                                                     578  585  582  580  579                                          Product                                                                       Yield, lbs/gal                                                                             5.00 4.95 4.90 4.92 4.84                                         CTAB, m.sup.2 /g                                                                           105.3                                                                              109.9                                                                              110.7                                                                              111.4                                                                              124.3                                        24M4-DBP, cc/100 g                                                                         104.9                                                                              105.6                                                                              106.1                                                                              110.0                                                                              117.6                                        Tint         110.8                                                                              115.4                                                                              111.9                                                                              110.3                                                                              110.3                                        Tint Residual*                                                                             +1.3 +3.9 +0.1 -0.7 -4.1                                         (Lbs CB/gal) × (CTAB)                                                                526  544  542  548  602                                          Lbs CB/Lb C in oil                                                                         .599 .593 .587 .590 .580                                         Lbs CB/Lb C in oil ×                                                                 63.1 65.3 65.0 65.7 72.1                                         CTAB                                                                          325 mesh grit, wt %                                                                        All samples below 0.0100                                         __________________________________________________________________________     .sup.(a) Nozzle Nos. G1415 and G1507 from Spraying Systems Co., Bellwood,     IL.                                                                           *Calculated assuming: (N.sub.2 SA  CTAB) = 0                             

    RUN NUMBER   52   53  54   55    56                                           __________________________________________________________________________    Black Type   N299 N299                                                                              N220 N220  N220                                         Oil Nozzle:                                                                   No. at 90° spacing                                                                  4    4   4    4     4                                            Diameter (orifice)                                                                         3-.082"                                                                            .082"                                                                             .0625"                                                                             1-.0890"                                                                            4-.0625"                                                  1-7/64"       3-.0625"                                           Full Cone Spray Angle                                                                      60°                                                                         60°                                                                        15°                                                                         15°                                                                          15°                                   .sup.(a) Type                                                                              Spray                                                                              Spray                                                                             Spray                                                                              Spray Spray                                        Rates & Conditions                                                            Total Air, MSCFH                                                                           199.1                                                                              249.3                                                                             198.8                                                                              199.3 199.0                                        Air Temp, °F.                                                                       1167 1163                                                                              1076 1067  1054                                         Fuel Gas, MSCFH                                                                            12.7 16.5                                                                              13.4 12.6  12.4                                         BTU/SCF      959  960 944  1006  1018                                         Air/Gas Ratio                                                                              15.6 15.1                                                                              14.8 15.8  16.0                                         Oil Rate, gph                                                                              344  344 311  306   309                                          °API  -2.3 -2.3                                                                              -2.3 -2.3  -2.3                                         Lb/gal       9.127                                                                              9.127                                                                             9.127                                                                              9.127 9.127                                        BMCI         127  127 127  127   127                                          C, wt %      91.4 91.4                                                                              91.4 91.4  91.4                                         Temp. °F.                                                                           331  343 338  374   393                                          Pressure, psig                                                                             85   199 165  109   159                                          Air/Oil Ratio, SCF/gal                                                                     579  574 639  651   644                                          Product                                                                       Yield, lbs/gal                                                                             4.92 4.95                                                                              4.92 4.66  4.67                                         CTAB, m.sup.2 /g                                                                           119.9                                                                              120.2                                                                             105.5                                                                              109.3 106.8                                        24M4-DBP, cc/100 g                                                                         110.9                                                                              104.9                                                                             101.1                                                                              126   119                                          Tint         117.1                                                                              117.8                                                                             108.1                                                                              112.2 103.2                                        Tint Residual*                                                                             +2.6 +3.3                                                                              -2.9 +6.1  -3.5                                         (Lbs CB/gal) × (CTAB)                                                                590  595 519  509   499                                          Lbs CB/Lb C in oil                                                                         .590 .593                                                                              .590 .559  .560                                         Lbs CB/Lb C in oil ×                                                                 70.7 71.3                                                                              62.2 61.1  59.8                                         CTAB                                                                          325 mesh grit, wt %                                                                        All samples below .010                                           __________________________________________________________________________     .sup.(a) Nozzle Nos. G5 and G9.5 from Spraying Systems Co., Bellwood, IL.     *Calculated assuming: (N.sub.2 SA  CTAB) = 0                             

    RUN NUMBER   57    58    59    60  61                                         __________________________________________________________________________    Black Type   N220  N220  N220  N220                                                                              N220                                       Oil Nozzle:                                                                   No. at 90° spacing                                                                  4     4     4     4   4                                          Diameter (orifice)                                                                         4-.0890"                                                                            1-.0890"                                                                            3-.0890"                                                                            .082"                                                                             .082"                                                         3-.0625"                                                                            1-.0625"                                             Full Cone Spray Angle                                                                      15°                                                                          15°                                                                          15°                                                                          60°                                                                        60°                                 .sup.(a) Type                                                                              Spray Spray Spray Spray                                                                             Spray                                      Rates & Conditions                                                            Total Air, MSCFH                                                                           199.4 251.8 250.4 199.5                                                                             249.2                                      Air Temp, °F.                                                                       1047  1077  1107  1096                                                                              1218                                       Fuel Gas, MSCFH                                                                            12.4  16.2  16.1  12.2                                                                              16.4                                       BTU/SCF      1028  1010  1004  1023                                                                              942                                        Air/Gas Ratio                                                                              16.1  15.5  15.6  16.3                                                                              15.2                                       Oil Rate, gph                                                                              310   389   387   317 415                                        °API  -2.3  -2.3  -2.3  -2.3                                                                              -2.3                                       Lb/gal       9.127 9.127 9.127 9.127                                                                             9.127                                      BMCI         127   127   127   127 127                                        C, wt %      91.4  91.4  91.4  91.4                                                                              91.4                                       Temp. °F.                                                                           345   353   357   341 327                                        Pressure, psig                                                                             161   174   112   98  158                                        Air/Oil Ratio, SCF/gal                                                                     643   647   647   629 600                                        Product                                                                       Yield, lbs/gal                                                                             4.69  4.64  4.68  4.71                                                                              4.81                                       CTAB, m.sup.2 /g                                                                           108.4 111.5 114.7 130.2                                                                             120.2                                      24M4-DBP, cc/100 g                                                                         126   122   114   108.1                                                                             100.2                                      Tint         106.8 107.4 115.9 115.1                                                                             119.4                                      Tint Residual*                                                                             +1.2  -0.7  +4.4  -3.9                                                                              +3.3                                       (Lbs CB/gal) × (CTAB)                                                                508   517   537   613 578                                        Lbs CB/Lb C in oil                                                                         .562  .556  .561  .565                                                                              .577                                       Lbs CB/Lb C in oil ×                                                                 60.9  62.0  64.3  73.5                                                                              69.3                                       CTAB                                                                          325 mesh grit, wt %                                                                        All samples below .010                                           __________________________________________________________________________     .sup.(a) Nozzle Nos. G1415 and G1507, from Spraying Systems Co., Bellwood     IL.                                                                           *Calculated assuming: (N.sub.2 SA  CTAB) = 0                             

    RUN NUMBER         62        63                                               __________________________________________________________________________    Black Type         N220      N220                                             Oil Nozzle:                                                                   No. at 90° spacing                                                                        4         4                                                Diameter (orifice) 3-.082"   .082"                                                               1-7/64"                                                    Full Cone Spray Angle                                                                            60°                                                                              60°                                       .sup.(a) Type      Spray     Spray                                            Rates & Conditions                                                            Total Air, MSCFH   251.3     251.0                                            Air Temp, °F.                                                                             1119      1122                                             Fuel Gas, MSCFH    15.8      15.8                                             BTU/SCF            1024      1025                                             Air/Gas Ratio      15.9      15.9                                             Oil Rate, gph      395       393                                              °API        -2.3      -2.3                                             Lb/gal             9.127     9.127                                            BMCI               127       127                                              C, wt %            91.4      91.4                                             Temp. °F.   319       330                                              Pressure, psig     109       155                                              Air/Oil Ratio, SCF/gal                                                                           636       639                                              Product                                                                       Yield, lbs/gal     4.74      4.68                                             CTAB, m.sup.2 /g   119.8     121.9                                            24M4-DBP, cc/100 g 110.9     114.1                                            Tint               114.3     115.9                                            Tint Residual*     -0.1      +1.5                                             (Lbs CB/gal) × (CTAB)                                                                      569       571                                              Lbs CB/Lb C in oil .568      .561                                             Lbs CB/Lb C in oil ×                                                                       68.2      68.4                                             CTAB                                                                          325 mesh grit, wt %                                                                              All samples below 0.0100                                   __________________________________________________________________________     .sup.(a) Nozzle Nos. G5 and G9.5 from Spraying Systems Co., Bellwood, IL.     *Calculated assuming: (N.sub.2 SA  CTAB) = 0                             

Runs 47 through 53 show production of N299 carbon black at an averageair/oil ratio of 579 SCF/gal, using 15° spray angle nozzles in runs 47through 56, and 60° spray angle nozzles in runs 51, 52 and 53. Theaverage value for CTAB obtained in runs 47 through 50 using 15° sprayangle is 109.3 m² /g, compared to 121.5 m² /g in runs 51, 52 and 53using 60° spray angle. Comparison of average yield between the runsusing 15° and 60° spray angle nozzles are 4.94 lbs/gal using 15° sprayangle, and 4.90 lbs/gal using 60° spray angle.

Similar results are shown in runs 54 through 61 for the same reactorproducing N220 carbon black at an average air/oil ratio of 637.5SCF/gal. The average value for CTAB obtained in runs 54 through 59 using15° spray angle nozzles is 109.4 m² /g, compared to 125.2 m² /g in runs60 and 61. Comparison of average yield between runs using 15° and 30°spray angle nozzles are 4.76 lbs/gal using 60° spray angle and 4.71lbs/gal using 15° spray angle.

The above comparison of results from runs 47 through 61 clearly show animprovement in CTAB values when using 60° spray angle nozzles comparedto 15° spray angle nozzles.

EXAMPLE V

The runs were made in a commercial size plant reactor. A is 28 inches. Bis 12 inches. C is 21 inches. D is 27 inches. E is 18.5 inches. F is 4inches. G is 119 inches. H is 16 inches. J is 12 inches. α is 18°26'.Results are shown in Table IV.

                                      TABLE IV                                    __________________________________________________________________________    RUN NUMBER   64  65 66  67  68 69  70                                         __________________________________________________________________________    Black Type   N299                                                                              N299                                                                             N299                                                                              N299                                                                              N299                                                                             N299                                                                              N299                                       Oil Nozzle:                                                                   No. at 60° spacing                                                                  6   6  6   6   6  6   6                                          Diameter (orifice)                                                                         .062"                                                                             .062"                                                                            .062"                                                                             .062"                                                                             .089"                                                                            5-.089"                                                                           5-.089"                                                                   1-.062                                                                            1-.062                                     Full Cone Spray Angle                                                                      30°                                                                        30°                                                                       30°                                                                        30°                                                                        15°                                                                       5-15°                                                                      5-15°                                                              1-30°                                                                      1-30°                               .sup.(a) Type                                                                              Spray                                                                             Spray                                                                            Spray                                                                             Spray                                                                             Spray                                                                            Spray                                                                             Spray                                      Rates & Conditions                                                            Total Air, MSCFH                                                                           676.6                                                                             680.9                                                                            671.0                                                                             668.8                                                                             665.4                                                                            690.4                                                                             698.6                                      Air Temp, °F.                                                                       1209                                                                              1209                                                                             1209                                                                              1207                                                                              1211                                                                             1205                                                                              1188                                       Fuel Gas, MSCFH                                                                            45.7                                                                              45.6                                                                             45.2                                                                              45.7                                                                              41.5                                                                             45.8                                                                              48.7                                       BTU/SCF      870 866                                                                              867 863 867                                                                              865 860                                        Air/Gas Ratio                                                                              14.8                                                                              14.9                                                                             14.8                                                                              14.6                                                                              16.0                                                                             15.1                                                                              14.3                                       Oil Rate, gph                                                                              1321                                                                              1299                                                                             1295                                                                              1294                                                                              1260                                                                             1271                                                                              1260                                       °API  5.6 5.6                                                                              6.2 6.9 6.6                                                                              7.8 7.8                                        Lb/gal       8.6 8.6                                                                              8.56                                                                              8.52                                                                              8.54                                                                             8.47                                                                              8.47                                       BMCI         102 102                                                                              101 99  101                                                                              97  97                                         C, wt %      87.7                                                                              87.7                                                                             87.7                                                                              87.7                                                                              88.5                                                                             87.7                                                                              87.7                                       Temp. °F.                                                                           450 450                                                                              450 450 450                                                                              450 450                                        Pressure, psig                                                                             260 250                                                                              212 210 240                                                                              215 370                                        Air/Oil Ratio, SCF/gal                                                                     512 524                                                                              518 517 528                                                                              543 550                                        Product                                                                       Yield, lbs/gal                                                                             4.51                                                                              4.36                                                                             4.36                                                                              4.36                                                                              4.46                                                                             4.58                                                                              4.47                                       CTAB, m.sup.2 /g                                                                           100.9                                                                             102.4                                                                            102.1                                                                             102.3                                                                             104.0                                                                            104.6                                                                             105.6                                      N.sub.2 SA, m.sup.2 /g                                                                     106.5                                                                             111.8                                                                            109.2                                                                             109.8                                                                             115.2                                                                            117.8                                                                             127.3                                      24M4-DBP, cc/100 g                                                                         103.4                                                                             100.9                                                                            100.6                                                                             100.6                                                                             101.4                                                                            99.2                                                                              103.0                                      Tint         119.0                                                                             116.6                                                                            120.3                                                                             118.0                                                                             115.1                                                                            116.4                                                                             117.5                                      Tint Residual                                                                              +12.3                                                                             +9.2                                                                             -12.5                                                                             +10.2                                                                             +7.4                                                                             +8.3                                                                              +11.6                                      (Lbs CB/gal) × (CTAB)                                                                455 446                                                                              445 445 464                                                                              479 472                                        Lbs CB/Lb C in oil                                                                         .598                                                                              .598                                                                             .598                                                                              .584                                                                              .590                                                                             .616                                                                              .594                                       Lbs CB/Lb C in oil ×                                                                 60.4                                                                              61.2                                                                             61.0                                                                              59.7                                                                              61.4                                                                             64.4                                                                              62.7                                       CTAB                                                                          325 mesh grit, wt %                                                                        --  .0169                                                                            --  --  .0051                                                                            --  --                                         __________________________________________________________________________     .sup.(a) Nozzle Nos. G3007 and G1514 from Spraying Systems Co., Bellwood,     IL.                                                                      

Runs 64 through 70 show production of N299 carbon black at an averageair/oil ratio of 527 SCF/gal, using 30° spray angle nozzles in runs 64through 67, and 15° spray angle nozzles in runs 68, 69 and 70. Theaverage value for CTAB obtained in runs 68, 69 and 70 using 15° sprayangle nozzles was 104.7 m² /g, compared to 101.9 m² /g in runs 64through 67 using 30° spray angles. Comparison of average yields betweenthe runs using 30° and 15° spray angle nozzles are 4.39 lbs/gal using30° spray angle nozzles and 4.50 lbs/gal using 15° spray angle nozzles.

The above comparison of results from runs 64 through 70 fail to show asubstantial difference in CTAB values or reactor yield when using 30°spray angle nozzles compared to 15° spray angle nozzles.

EXAMPLE VI

The runs were made in a commercial size plant reactor. A is 21 inches. Bis 8 inches. C is 15 inches. D is 27 inches. E is 18.5 inches. F is 4inches. G is 7.8 inches. H is shown in Table V. J is 12 inches. α is18°27'. Results are shown in Table V.

                  TABLE V                                                         ______________________________________                                        RUN NUMBER     71     72     73   74   75   76                                ______________________________________                                        Oil Nozzle:                                                                   No. of nozzles 4      4      4    4    4    4                                 Full Cone Spray Angle                                                                        2-45°                                                                         2-45°                                                                         15°                                                                         15°                                                                         15°                                                                         15°                                       2-60°                                                                         2-60°                                                                         --   --   --   --                                Location(dimension H)                                                                        8"     8"     16"  16"  16"  16"                               Rates & Conditions                                                            Total Air, MSCFH                                                                             249.1  249.1  199.0                                                                              199.4                                                                              251.8                                                                              198.8                             Air Temp, °F.                                                                         1187   1174   1054 1047 1047 --                                Fuel Gas, MSCFH                                                                              16.2   16.3   12.4 12.4 16.2 13.4                              BTU/SCF        82.6   82.5   80.9 81.1 82.7 81.3                              Air/Gas Ratio  15.4   15.3   16.1 16.1 15.5 14.8                              Oil Rate, gph  453    433    309  310  389  311                               °API    -2.3   -2.3   -2.3 -2.3 -2.3 -2.3                              BMCI           127.4  127.4  127.4                                                                              127.4                                                                              127.4                                                                              127.4                             C, wt %        91.4   91.4   91.4 91.4 91.4 91.4                              Temp. °F.                                                                             326    323    393  345  353  338                               Pressure, psig 105.5  102    159  161  174  165                               Air/Oil Ratio, SCF/gal                                                                       550    575    644  643  647  639                               Catalyst (8%), ccpm                                                                          0.0    0.0    0.0  0.0  5.95 48.9                              Product                                                                       Yield, lbs/gal 5.10   5.02   4.67 4.69 4.64 4.92                              CTAB, m.sup.2 /g                                                                             104.6  108.7  106.8                                                                              108.4                                                                              111.5                                                                              105.5                             24M4-DBP, cc/100 g                                                                           99.5   99.3   119  126  122  101                               Tint           114.4  113.8  103.2                                                                              106.8                                                                              107.4                                                                              108.1                             Tint Residual  +3.7   +1.1   -3.5 -1.2 -0.7 -2.9                              (Lbs CB/gal) × (CTAB)                                                                  533    546    499  508  517  519                               DBP, cc/100 g  137.5  133.5  153  168  157  116                               Δ DBP    38     34.2   34   42   35   15                                ______________________________________                                    

In the runs tabulated in Table V, the reactor was producing a carbonblack having a CTAB surface area ranging from 104.6 to 111.5, arelatively narrow range. This black was produced in runs 71 and 72 atthe 8-inch feed injection position, in runs 73 and 74 at the 16-inchfeed injection position and in runs 75 and 76 while adding 8% KClsolution. Comparing runs 73 and 74 to 71 and 72, it is seen that movingthe oil injection position upstream greatly increased the DBP structureof the black, as measured by ASTM 2414-79. Comparing runs 75 and 76 to73 and 74 shows that potassium addition lowers both DBP structure and24M4-DBP structure determined according to ASTM 3493-79. Further, in run76, when sufficient potassium was added to bring the 24M4-DBP of theblack down to about 100 cc/100 g, as in runs 71 and 72, the DBP of thesample was only about 116. This unusual relationship is shown in theΔDBP line, which in run 76 was only about 15.

That which is claimed is:
 1. A carbon black reactor having a reactionflow path with a longitudinal axis, said carbon black reactorcomprising(a) means defining a generally cylindrical combustion zonehaving an upstream end and a downstream end; (b) means defining a mixingzone characterized by a frustoconical sidewall converging from thedownstream end of the generally cylindrical combustion zone to a reactorthroat; (c) means connecting the downstream end of the said combustionzone to the means defining the mixing zone; (d) means defining agenerally cylindrical pyrolysis zone defined by a generally cylindricalsidewall connected to the reactor throat by a generally annular end wallwherein each of the combustion zone, mixing zone and pyrolysis zone isaligned along a longitudinal path within the reactor; (e) a plurality offeedstock injectors extending normally with respect to the longitudinalaxis through the means defining the mixing zone, each of said feedstockinjectors designed to emit a cone-shaped spray of feedstock whichdiverges at an angle in the range of about 30° to about 120°; (f) meansfor introducing hot gases generally axially into the upstream end of thecombustion zone means; and (g) a source of carbonaceous feedstockconnected to said plurality of feedstock injectors.
 2. A carbon blackreactor as in claim 1 wherein the feedstock injectors are designed toemit a spray which diverges at an angle in the range of about 45° toabout 90°.
 3. A carbon black reactor as in claim 2 wherein the feedstockinjectors are designed to emit a spray which diverges at an angle ofabout 60°.
 4. A carbon black reactor as in claim 3 further comprisingsaid means defining a source of feedstock having a pressure in the rangeof 150 to 600 psig connected to the feedstock injectors.
 5. A carbonblack reactor as in claim 4 wherein said means defining a source offeedstock is further characterized by the source of feedstock having atemperature in the range of 350° to 750° F.
 6. A carbon black reactor asin claim 1 wherein each of the means defining the generally cylindricalcombustion zone, the mixing zone and the generally cylindrical pyrolysiszone comprises a refractory sidewall.